Despite his decision, Franken stopped well short of admitting to the stories seven women have told about him in recent weeks, starting with TV personality Leann Tweeden.

"Some of the allegations against me are simply not true," Franken said. "Others I remember very differently."

Franken said his statements about accusers had "given the false impression" that he was admitting to "doing things that, in fact, I haven't done." Accusations about Franken include numerous incidents of groping, and both Tweeden and a former Congressional staffer accused Franken of trying to kiss them on the lips without their consent.

"I am proud that during my time in the Senate I have used my power to be a champion of women, and that I have earned a reputation as someone who respects the women I work alongside everyday. I know there's been a very different picture of me painted during the past few weeks. But I know who I really am."

Franken believed a Senate ethics investigation would have redeemed him.

“Nothing I have done as a senator, nothing, has brought dishonor on this institution," he said.

But, he continued, it had "become clear" that Franken could not be an "effective senator" for his constituents in Minnesota.

Franken's speech made references to President Donald Trump and Roy Moore, the Republican U.S. Senate candidate from Alabama who has been accused by multiple women of pursuing them sexually when they were teenagers.

"I of all people am aware that there is some irony in the fact that I am leaving while a man who has bragged on tape about his history of sexual assault sits in the Oval Office, and a man who has repeatedly preyed on young girls campaigns for the Senate, with the full support of his party."

Franken's replacement will be chosen by DFL Gov. Mark Dayton. Insiders have suggested Dayton might pick his trusted Lieutenant Governor, Tina Smith, who had considered running to succeed Dayton as governor before deciding against it. Whoever gets the seat will have to immediately prepare for an election in 2018.

At one point, Franken alluded to the possibilty his replacement would be a woman.

"Minnesota deserves a senator who can focus with all her energy on addressing the challenges they face every day."

Franken said despite a "difficult few weeks," he is a "very lucky man." The second-term senator said he would continue to have a public role as "a citizen and an activist" for progressive politics.